/*
 * Copyright (c) 2012-2018 Red Hat, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Red Hat, Inc. - initial API and implementation
 */
package org.eclipse.che.ide.runtime;

/**
 * <code>Assert</code> is useful for for embedding runtime sanity checks in code. The predicate
 * methods all test a condition and throw some type of unchecked exception if the condition does not
 * hold.
 *
 * <p>Assertion failure exceptions, like most runtime exceptions, are thrown when something is
 * misbehaving. Assertion failures are invariably unspecified behavior; consequently, clients should
 * never rely on these being thrown (and certainly should not be catching them specifically).
 *
 * <p>This class can be used without OSGi running.
 *
 * <p>This class is not intended to be instantiated or sub-classed by clients.
 *
 * @noinstantiate This class is not intended to be instantiated by clients.
 * @since org.eclipse.equinox.common 3.2
 */
public final class Assert {
  /* This class is not intended to be instantiated. */
  private Assert() {
    // not allowed
  }

  /**
   * Asserts that an argument is legal. If the given boolean is not <code>true</code>, an <code>
   * IllegalArgumentException</code> is thrown.
   *
   * @param expression the outcome of the check
   * @return <code>true</code> if the check passes (does not return if the check fails)
   * @throws IllegalArgumentException if the legality test failed
   */
  public static boolean isLegal(boolean expression) {
    return isLegal(expression, ""); // $NON-NLS-1$
  }

  /**
   * Asserts that an argument is legal. If the given boolean is not <code>true</code>, an <code>
   * IllegalArgumentException</code> is thrown. The given message is included in that exception, to
   * aid debugging.
   *
   * @param expression the outcome of the check
   * @param message the message to include in the exception
   * @return <code>true</code> if the check passes (does not return if the check fails)
   * @throws IllegalArgumentException if the legality test failed
   */
  public static boolean isLegal(boolean expression, String message) {
    if (!expression) throw new IllegalArgumentException(message);
    return expression;
  }

  /**
   * Asserts that the given object is not <code>null</code>. If this is not the case, some kind of
   * unchecked exception is thrown.
   *
   * @param object the value to test
   */
  public static void isNotNull(Object object) {
    isNotNull(object, ""); // $NON-NLS-1$
  }

  /**
   * Asserts that the given object is not <code>null</code>. If this is not the case, some kind of
   * unchecked exception is thrown. The given message is included in that exception, to aid
   * debugging.
   *
   * @param object the value to test
   * @param message the message to include in the exception
   */
  public static void isNotNull(Object object, String message) {
    if (object == null)
      throw new AssertionFailedException("null argument:" + message); // $NON-NLS-1$
  }

  /**
   * Asserts that the given boolean is <code>true</code>. If this is not the case, some kind of
   * unchecked exception is thrown.
   *
   * @param expression the outcome of the check
   * @return <code>true</code> if the check passes (does not return if the check fails)
   */
  public static boolean isTrue(boolean expression) {
    return isTrue(expression, ""); // $NON-NLS-1$
  }

  /**
   * Asserts that the given boolean is <code>true</code>. If this is not the case, some kind of
   * unchecked exception is thrown. The given message is included in that exception, to aid
   * debugging.
   *
   * @param expression the outcome of the check
   * @param message the message to include in the exception
   * @return <code>true</code> if the check passes (does not return if the check fails)
   */
  public static boolean isTrue(boolean expression, String message) {
    if (!expression)
      throw new AssertionFailedException("assertion failed: " + message); // $NON-NLS-1$
    return expression;
  }
}
